INTANGIBLE ASSETS - Summary of Acquired Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 7,075,027		$ 7,075,027		$ 7,075,027
Accumulated Amortization	(2,466,442)		(2,466,442)		(2,008,573)
Net Carrying Amount	4,608,585		4,608,585		5,066,454
Amortization of Intangible Assets	226,052	$ 317,219	457,869	$ 555,238
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,970,884		5,970,884		5,970,884
Accumulated Amortization	(1,797,079)		(1,797,079)		(1,409,021)
Net Carrying Amount	4,173,805		4,173,805		4,561,863
Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,067,083		1,067,083		1,067,083
Accumulated Amortization	(654,498)		(654,498)		(588,574)
Net Carrying Amount	412,585		412,585		478,509
Other amortizable intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	37,060		37,060		37,060
Accumulated Amortization	(14,865)		(14,865)		(10,978)
Net Carrying Amount	$ 22,195		$ 22,195		$ 26,082
Minimum | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			8 years
Minimum | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			2 years
Minimum | Other amortizable intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			1 year
Maximum | Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			18 years
Maximum | Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			5 years
Maximum | Other amortizable intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible asset, useful life			15 years